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Zhou H, Zhang J, Shao Y, Wang J, Xu W, Liu Y, Yu S, Ye Q, Pang R, Wu S, Gu Q, Xue L, Zhang J, Li H, Wu Q, Ding Y. Development of a high resolution melting method based on a novel molecular target for discrimination between Bacillus cereus and Bacillus thuringiensis. Food Res Int 2022; 151:110845. [PMID: 34980383 DOI: 10.1016/j.foodres.2021.110845] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 11/03/2021] [Accepted: 11/27/2021] [Indexed: 11/04/2022]
Abstract
Delimitation within the Bacillus cereus group is confusing due to the highly similar genetic background of its constituent bacteria. This study aimed to develop a rapid and efficient method for the identification of Bacillus cereus and Bacillus thuringiensis, two closely related species within the B. cereus group. Using average nucleotide identity analysis (ANI) and ribosomal multilocus sequence typing (rMLST), the authenticity of the genomes of B. cereus and B. thuringiensis was determined. Emetic B. cereus and Bacillus bombysepticus were also included to provide novel genomic insights into the boundaries within the B. cereus group. Using pan-genome analysis, ispD, a novel core and single-copy molecular target, was identified for the differentiation between B. cereus and B. thuringiensis. Based on the single nucleotide polymorphism within ispD, a high resolution melting (HRM) method for the determination of B. cereus and B. thuringiensis was developed. This method can not only distinguish B. cereus and B. thuringiensis, but can also separate B. cereus from other foodborne pathogenic bacteria. The detection limit of this method could reach 1 pg of pure genomic DNA and 3.7 × 102 cfu/mL of pure culture. Moreover, this new method could effectively differentiate B. cereus and B. thuringiensis in spiked, mixed, and real food samples. Collectively, the established HRM method can provide a new reference paradigm for the sensitive and specific nucleic acid detection of pathogens with identical genomes.
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Affiliation(s)
- Huan Zhou
- College of Life Science and Technology, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Junhui Zhang
- Department of Food Science & Technology, Institute of Food Safety & Nutrition, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Yanna Shao
- College of Life Science and Technology, Jinan University, Guangzhou 510632, China; Department of Food Science & Technology, Institute of Food Safety & Nutrition, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Juan Wang
- College of Food Science, South China Agricultural University, Guangzhou 510432, China
| | - Wenxing Xu
- Department of Food Science & Technology, Institute of Food Safety & Nutrition, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Yang Liu
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Shubo Yu
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Qinghua Ye
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Rui Pang
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Shi Wu
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Qihui Gu
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Liang Xue
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Jumei Zhang
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Hongye Li
- College of Life Science and Technology, Jinan University, Guangzhou 510632, China
| | - Qingping Wu
- Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China
| | - Yu Ding
- College of Life Science and Technology, Jinan University, Guangzhou 510632, China; Department of Food Science & Technology, Institute of Food Safety & Nutrition, Jinan University, Guangzhou 510632, China; Guangdong Provincial Key Laboratory of Microbial Safety and Health, State Key Laboratory of Applied Microbiology Southern China, Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou 510070, China.
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Hu S, Lv Z, Wang Y, Shen J, Ke Y. Novel Quadruplex PCR for detecting and genotyping mobile colistin resistance genes in human samples. Diagn Microbiol Infect Dis 2021; 101:115419. [PMID: 34610496 DOI: 10.1016/j.diagmicrobio.2021.115419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/18/2021] [Accepted: 04/26/2021] [Indexed: 11/18/2022]
Abstract
Since 2016, several mobile colistin resistance (mcr) genes have been identified worldwide. It's worth noting that only mcr-1, mcr-3, mcr-8, and mcr-10 have been reported isolated directly from clinical samples which created greater risk to human health than other mcr gene types. A novel Quadruplex polymerase chain reaction (Quad-PCR) protocol was developed to detect and genotype transferable colistin-resistance genes (mcr-1, mcr-3, mcr-8, mcr-10) in Enterobacteria for clinical laboratory purposes. The protocol was validated by testing 11 clinical isolates of Escherichia coli and 3 clinical isolates of Klebsiella of human origin, each well characterized and prospectively validated. The Quad-PCR assay showed full concordance with whole-genome sequence data and displayed higher sensitivity and 100% specificity. The Quad-PCR assay achieved genotyping of mcr alleles (as singleton and mixture with double or triple gene types) described in one test.
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Affiliation(s)
- Shuangfang Hu
- Key Laboratory of Molecular Epidemiology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen City, Guangdong Province, PR China; Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing, PR China
| | - Ziquan Lv
- Key Laboratory of Molecular Epidemiology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen City, Guangdong Province, PR China
| | - Yang Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing, PR China
| | - Jianzhong Shen
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing, PR China.
| | - Yuebin Ke
- Key Laboratory of Molecular Epidemiology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Shenzhen City, Guangdong Province, PR China.
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Hu S, Lv Z, Wang Y, Shen J, Ke Y. Rapid detection of human origin colistin-resistance genes mcr-1, mcr-3, mcr-8, mcr-10 in clinical fecal samples. Arch Microbiol 2021; 203:4405-4417. [PMID: 34125247 DOI: 10.1007/s00203-021-02407-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 05/04/2021] [Accepted: 05/25/2021] [Indexed: 11/27/2022]
Abstract
Plasmid-mediated colistin-resistance genes have been reported in human origin clinical samples worldwide which raises its threats to human infections. Notably, mcr-1, mcr-3, mcr-8, and mcr-10 have been reported isolated directly from clinical samples which creates more seriously threaten to human health than other mcr gene types. A multiplex polymerase chain reaction (Multi-PCR) protocol was developed to detect and genotype mobile colistin-resistance genes (mcr-1, mcr-3, mcr-8, mcr-10) in Enterobacteria for clinical laboratory purposes. We first designed four pairs of new primers for the amplification of mcr-1, mcr-3, mcr-8, and mcr-10 gene respectively to achieve stepwise separation of amplicons between 216 and 241 bp, and complete this Multi-PCR system with the assistance of another pair of universal primer. Among which the forward primers for mcr-8 and mcr-10 amplicons were identical. The protocol was validated by testing 11 clinical isolates of Escherichia coli and 3 clinical isolates of Klebsiella from human origin, each well characterized and prospectively validated. The Multi-PCR assay showed full concordance with whole-genome sequence data and displayed higher sensitivity and 100% specificity. The assay could detect all variants of the various mcr alleles described. The Multi-PCR assay successfully genotyped of mcr alleles described in one test.
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Affiliation(s)
- Shuangfang Hu
- Key Laboratory of Molecular Epidemiology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Guangdong Province, No. 8 Longyuan Road, Nanshan district, Shenzhen City, 518055, People's Republic of China
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing, 10083, People's Republic of China
| | - Ziquan Lv
- Key Laboratory of Molecular Epidemiology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Guangdong Province, No. 8 Longyuan Road, Nanshan district, Shenzhen City, 518055, People's Republic of China
| | - Yang Wang
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing, 10083, People's Republic of China
| | - Jianzhong Shen
- Beijing Advanced Innovation Center for Food Nutrition and Human Health, College of Veterinary Medicine, China Agricultural University, Beijing, 10083, People's Republic of China.
| | - Yuebin Ke
- Key Laboratory of Molecular Epidemiology of Shenzhen, Shenzhen Center for Disease Control and Prevention, Guangdong Province, No. 8 Longyuan Road, Nanshan district, Shenzhen City, 518055, People's Republic of China.
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Labchip-based diagnosis system for on-site application: Sensitive and easy-to-implement detection of single recoverable Cronobacter in infant formula without post-enrichment treatment. Int J Food Microbiol 2020; 327:108659. [PMID: 32413591 DOI: 10.1016/j.ijfoodmicro.2020.108659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 11/20/2022]
Abstract
Microfluidic labchips have achieved much advancement in the molecular diagnosis of foodborne pathogens. Whereas difficulties in the flow control during the transportation of liquid fluids can occur and should be overcome. Manipulations of reaction temperature and the complex procedures from sample pre-treatment to analysis in a single chip device are major obstacles for the on-site application. Thus, the efficient temperature control of samples without any flow of reaction fluids in microfluidic channels of plastic chip and the simplest protocol omitting post-enrichment processing steps may overcome these limitations represented by the stability and the complexity, respectively. This study aims to develop a novel type of labchip and thermocycler specialized for the gene amplification in microfluidic channels and to evaluate the detectability by sensing the minimum recoverable level of Cronobacter in powdered infant formula (PIF). We developed a thermocycling device accelerating reactions through dual heating-blocks optimized to control temperatures of samples in microfluidic-channels by direct contact with labchip sequentially and repetitively. The structural design of microfluidic channels was to eliminate interference factors associated with the optical detection of fluorescent signals (without distortion due to air bubbles in the reaction chamber). To improve the applicability, a portable device and simplified operation to allow direct loading of samples in the chip without post-enrichment procedures were also adopted. Detection performance was evaluated by a sensitivity/specificity tests using 50 isolates of Cronobacter. Cross-reactivity tests for non-Cronobacter organisms and gDNA [human, raw materials of PIF (cow, soybean)] showed that there was no interference-factor causing false-positive results. In terms of the applied research conducted by using PIF, the enrichment of samples without broth medium (distilled water) displayed outstanding performance and 12 h of incubation facilitated detecting target at concentration as low as 1 CFU/300 g PIF (as initial contamination level) without post-enrichment treatment. Validation of the operation conditions using 30 commercial PIF products was also consistent. The present study presents a novel approach of microfluidic technology with perspective to not only the performance and the practicability [easy-to-implement protocol, portable materials, cost-effectiveness (the use of a miniaturized plastic chip requires a minimum level of materials)] for on-site diagnosis.
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Liu J, Zhan Z, Liang T, Xie G, Aguilar ZP, Xu H. Dual-signal amplification strategy: Universal asymmetric tailing-PCR triggered rolling circle amplification assay for fluorescent detection of Cronobacter spp. in milk. J Dairy Sci 2020; 103:3055-3065. [PMID: 32037161 DOI: 10.3168/jds.2019-17590] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Accepted: 12/08/2019] [Indexed: 01/19/2023]
Abstract
Cronobacter spp. are important opportunistic foodborne pathogens in powdered infant formula that cause many serious diseases in neonates and infants. In this study, a novel assay based on dual signal amplification strategy was developed by coupling asymmetric tailing PCR (AT-PCR) with rolling circle amplification (RCA) for the detection of Cronobacter spp. in milk. The tailing single-stranded DNA was generated through AT-PCR and used to initiate RCA, generating tandem repetitive G-quadruplex sequences. In the presence of the fluorescence dye thioflavin T that could intercalate into the G-quadruplex structures, the fluorescence signal was detected with a microplate reader. The AT-PCR coupled with RCA assay was specific for Cronobacter spp. detection because of the highly specific primers chosen for the AT-PCR. The limits of detection were 4.3 × 101 cfu/mL in pure culture and 4.5 × 102 cfu/mL in spiked milk, respectively. The fixed sequences designed in the hairpin DNA allowed this AT-PCR coupled with RCA assay to serve as a universal platform for the detection of other pathogens by modifying the specificity of the PCR primers.
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Affiliation(s)
- Ju Liu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China
| | - Zhongxu Zhan
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China; Jiangxi Institute for Food Control, Nanchang, 330001, PR China
| | - Taobo Liang
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China
| | - Guoyang Xie
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China
| | | | - Hengyi Xu
- State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang, 330047, PR China.
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